"They don't let my ministers make speeches in Europe (...) Once the referendum on April 16 is over, we will consider, everything has a price," Erdogan told a referendum rally in the western city of Zonguldak, Reuters reported.

Erdogan has repeatedly lashed out at European countries including Germany in campaigning for the referendum, accusing them of "Nazi-like" tactics for banning his ministers from speaking to rallies of Turkish voters abroad.